#ifndef LINUX_PREEMPT_MASK_H
  #define LINUX_PREEMPT_MASK_H
  
  #include <linux/preempt.h>
  
  /*
   * We put the hardirq and softirq counter into the preemption
   * counter. The bitmask has the following meaning:
   *
   * - bits 0-7 are the preemption count (max preemption depth: 256)
   * - bits 8-15 are the softirq count (max # of softirqs: 256)
   *
   * The hardirq count could in theory be the same as the number of
   * interrupts in the system, but we run all interrupt handlers with
   * interrupts disabled, so we cannot have nesting interrupts. Though
   * there are a few palaeontologic drivers which reenable interrupts in
   * the handler, so we need more than one bit here.
   *
   * PREEMPT_MASK:	0x000000ff
   * SOFTIRQ_MASK:	0x0000ff00
   * HARDIRQ_MASK:	0x000f0000
   *     NMI_MASK:	0x00100000
   * PREEMPT_ACTIVE:	0x00200000
   */
  #define PREEMPT_BITS	8
  #define SOFTIRQ_BITS	8
  #define HARDIRQ_BITS	4
  #define NMI_BITS	1
  
  #define PREEMPT_SHIFT	0
  #define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
  #define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
  #define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
  
  #define __IRQ_MASK(x)	((1UL << (x))-1)
  
  #define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
  #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
  #define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
  #define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
  
  #define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
  #define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
  #define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
  #define NMI_OFFSET	(1UL << NMI_SHIFT)
  
  #define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)
  
  #define PREEMPT_ACTIVE_BITS	1
  #define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)
  #define PREEMPT_ACTIVE	(__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
  
  #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
  #define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
  #define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
  				 | NMI_MASK))
  
  /*
   * Are we doing bottom half or hardware interrupt processing?
   * Are we in a softirq context? Interrupt context?
   * in_softirq - Are we currently processing softirq or have bh disabled?
   * in_serving_softirq - Are we currently processing softirq?
   */
  #define in_irq()		(hardirq_count())
  #define in_softirq()		(softirq_count())
  #define in_interrupt()		(irq_count())
  #define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
  
  /*
   * Are we in NMI context?
   */
  #define in_nmi()	(preempt_count() & NMI_MASK)
  
  #if defined(CONFIG_PREEMPT_COUNT)
  # define PREEMPT_CHECK_OFFSET 1
  #else
  # define PREEMPT_CHECK_OFFSET 0
  #endif
  
  /*
   * The preempt_count offset needed for things like:
   *
   *  spin_lock_bh()
   *
   * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
   * softirqs, such that unlock sequences of:
   *
   *  spin_unlock();
   *  local_bh_enable();
   *
   * Work as expected.
   */
  #define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_CHECK_OFFSET)
  
  /*
   * Are we running in atomic context?  WARNING: this macro cannot
   * always detect atomic context; in particular, it cannot know about
   * held spinlocks in non-preemptible kernels.  Thus it should not be
   * used in the general case to determine whether sleeping is possible.
   * Do not use in_atomic() in driver code.
   */
  #define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != 0)
  
  /*
   * Check whether we were atomic before we did preempt_disable():
   * (used by the scheduler, *after* releasing the kernel lock)
   */
  #define in_atomic_preempt_off() \
  		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
  
  #ifdef CONFIG_PREEMPT_COUNT
  # define preemptible()	(preempt_count() == 0 && !irqs_disabled())
  #else
  # define preemptible()	0
  #endif
  
  #endif /* LINUX_PREEMPT_MASK_H */